The present invention relates to a telescope main body and a spotting scope.
A telescope (spotting scope) with a digital camera is known, which is capable of shooting an electronic image that is the same as a visual image viewed through an eyepiece thereof. Such a telescope is disclosed, for example, in a Japanese Utility Model Publication No. 3074642 (hereafter, referred to as a document 1). The telescope with a digital camera is provided with a beam splitter for splitting a light beam that has passed through an objective optical system and a focusing lens, and leading one of the resultant split beams to an ocular optical system and the other to an imaging device such as a CCD (charge coupled device) imaging device.
Such telescope with digital camera may incur a focal shift between a visual image viewed through the eyepiece and an object image captured by the imaging device, because of diopter variation of a user, such as hyperopia or myopia. In other words, though the image viewed through the eyepiece appears correctly focused, the image captured by the imaging device may not be correctly focused.
In order to eliminate such focal shift, a fieldscope with a DV camera disclosed in the patented document 1 is provided with a diopter adjusting ring located close to an ocular lens, to be manipulated for moving the ocular lens group such that a scale (shooting frame) marked on a focusing glass becomes clearly seen, to thereby correct a user's diopter variation, which is a variation among individuals (see paragraph 0034 of the document 1).
However, the fieldscope with a DV camera according to the document 1 still has a drawback that the manipulation of the diopter adjustment is troublesome, and the fieldscope is therefore not user-friendly. Besides, since the visual image viewed through the eyepiece can any way be focused upon manipulating a focusing ring regardless of whether the diopter adjustment is performed or not, the troublesome diopter adjustment operation is prone to be skipped or forgotten, which may result in producing a blurred picture with a focal shift.
Further, even though the diopter adjustment has been performed, the adjustment may still be unsharp (inaccurate) depending on focusing capability of the user's eye. In this case, also the shot image suffers a focal shift.
Furthermore, even though the diopter adjustment has been correctly performed at first, the user's diopter may vary with time owing to eye strain, instrument myopia or a change of a condition of use, therefore subsequent shots may result in blurred pictures.